One of the more difficult packaging problems is that related to packaging of condiments such as ketchup, mustard and the like. Not only must the package be attractive and resistant to chemical attack, but it must be free of substances which affect flavor. Normally such packaging comprises several layers to achieve the necessary properties. However, the very need to use the several layers (which typically include printable plys, metal plys and various adhesion-promoting coats and other barrier-layers such as acid-barrier layers) makes the resultant laminated less flexible than is optimum for handling on automatic packaging and heat-sealing apparatus.
The prior art is replete with attempts to provide improved webs for use in condiment packaging. One of the more successful materials has been a web formed of the following:
Printed cellophane PA2 White-pigmented, low-density polyethylene (10% titanium dioxide pigment) PA2 Aluminum foil PA2 urethane adhesive PA2 0.002 inch layer of medium density polyethylene PA2 (1) a printable surface ply PA2 (2) a metallic foil ply PA2 (3) a heatsealable ply
This is typical of those condiment packages which required a printable surface, a metallic foil barrier and a heat-sealable backing ply.